The present invention concerns a sample carrier for IR spectroscopy which has a sample application zone as well as at least one groove-shaped channel into which liquid is drawn from the sample application zone as a result of capillary forces. The present invention also concerns a method for IR spectroscopy using a sample carrier according to the invention and a system for IR spectroscopy using the sample carrier according to the invention.
Sample carriers for carrying out IR spectroscopy are already known in the prior art in which sample liquid is placed in a depression and an IR-spectroscopic analysis is carried out after the sample liquid has dried. A disadvantage of such sample carriers is that the mostly small sample volumes have to be dosed precisely for a quantitative analysis. In addition the effect occurs with sample carriers with depressions that liquids containing protein form a drying ring in which a relatively high amount of sample is present in the ring region whereas only very small amounts of sample are present inside the ring. This or other drying patterns can make it difficult or even impossible to qualitatively and quantitatively analyse the sample liquid by means of IR spectroscopy.
Other sample carriers for IR spectroscopy are also known in the prior art which are in the form of nets onto which the sample liquid is applied such that the liquid spreads out in the meshes of the net. The nets already enable a dosing of the sample liquid in such a manner that a specific sample volume is imbibed per mesh with a known viscosity of the sample. However, a disadvantage of such sample carriers is that their manufacture and handling can be complicated.
The object of the present invention was to propose sample carriers which are easy to manufacture, enable a simple handling and achieve a relatively uniform and predetermined distribution of the sample. Sample carriers according to the invention can also advantageously provide dosing of the sample liquid in such a manner that a certain amount of the sample liquid is recovered on a certain area of the sample carrier.
Sample carriers for IR spectroscopy according to the invention have a sample application zone and at least one groove-shaped channel into which liquid is drawn from the sample application zone as a result of capillary forces. In a method according to the invention for the IR spectroscopy of a sample liquid, a sample carrier according to the invention is firstly provided, the sample liquid is applied to the application zone of the sample carrier and the zone of the sample carrier in which the at least one groove-shaped channel is located (spreading zone) is irradiated with IR radiation. Subsequently the radiation which is reflected from the spreading zone or transmitted through the spreading zone is detected and evaluated in order to carry out a qualitative and/or quantitative analysis of the sample liquid.
The invention additionally comprises a system for carrying out IR spectroscopy of a sample liquid with the following elements:
A sample carrier with an application zone for the application of a liquid sample and a spreading zone connected to the application zone which has at least one groove-shaped channel into which liquid is drawn from the sample application zone as a result of capillary forces,
a source of IR radiation to irradiate at least a part of the spreading zone of the sample carrier,
a detector to detect the radiation that is reflected from the spreading zone or transmitted through the spreading zone,
an evaluation unit to evaluate the detector signals for the qualitative and/or quantitative analysis of the sample liquid.